Improvement of pearl millet and groundnut productivity under micro-dose fertilizer application and water management technologies in Dodoma, Tanzania

PhDThesis

Crop production in semi-arid areas is faced with different challenges that resulted into low crop productivity, low household income and food insecurity. The main production challenges in these areas are declining soil fertility and moisture stresses. The integration of different techniques, which restore soil nutrients at low costs and improve soil moisture can be used as a strategy to cope with these constraints and ensuring sustainable crop production. The purpose of this work was to investigate the effects of applying inorganic fertilizer at reduced amounts (micro-dose rates) under different in-situ rainwater harvesting and soil moisture management technologies by using tied ridges and infiltration pits in pearl millet and groundnut growth and grain yields. It also, focused on assessing profitability of integration of fertilizer rates with tied ridges and infiltration pits in smallholder farming communities. Field experiments were conducted in a semi-arid central part of Tanzania from 2015 to 2017 covering Ilolo and Idifu villages located in Chamwino district, Dodoma region. It was observed that, using tied ridges and infiltration pits increased pearl millet and groundnut yield significantly compared with flat cultivation. Application of fertilizer micro-doses from 25% to 75% of the recommended rate for pearl millet and from 50% to 75% of recommended rate for groundnut increased grain and kernel yields significantly compared with zero application. Integration of flat cultivation and tied ridges with micro-dose at 25% of recommended rate in pearl millet gave yield advantage ranging from 295 to 455 kg/ha and 537 to 959 kg/ha, respectively, compared to farmer practices. It also resulted into positive net profit. Flat cultivation with zero fertilizer application resulted in lowest groundnut yield and had a negativeii net profit. The integrations of tied ridges and fertilizer micro-dose at 50% of net profit. The integrations of tied ridges and fertilizer micro-dose at 50% of recommended rate gave significantly higher kernel yield, ranging from 906 to 1,197 kg/ha and higher net profit ranging from 424 to 558 USD/ha compared to farmer practice. Tied ridges and infiltration pits conserved soil moisture by 38% and 45%, respectively, more than flat cultivation at 30 cm depth after ten days of rainfall. Land use efficiency was 93% - 157% higher in intercropping system than in sole cropping. Intercropping of pearl millet and groundnut along with tied ridges and infiltration pits with micro-dose rates from 25% to 75% of recommended rate had financial returns of 648- 998 USD/ha higher than sole pearl millet in flat cultivation without fertilizer application. Therefore, the use of micro-dose at 25% of the recommended rate (i.e 15 kgN/ha and 10 kg P 2 O 5 /ha) for pearl millet, and 50% of recommended rate (22.5 kg P 2 O 5 /ha) for groundnuts along with tied ridges and flat cultivation is recommended to resource poor farmers of central Tanzania. The study also recommends intercropping of pearl millet and groundnut along with tied ridges and infiltration pits with micro-dose rates at 25% and advanced to higher rates up to recommended rate as their resources increases. This study is further recommending a review of fertilizer package to include lower amount such as 5 kg, 10 kg, 15 kg or 25 kg bags. This will enable smallholder farmers to purchase small amount of fertilizer as per their requirement. The study is further recommending the establishment of government agricultural center in each village to serve famers on all agricultural issues such as purchasing of improved inputs on time.